From 71ff89a803133c944a78ec66debc7b9fe6e3576a Mon Sep 17 00:00:00 2001
From: MrSimbax <matt@przybyl.io>
Date: Sun, 7 Feb 2021 12:47:32 +0100
Subject: [PATCH] Remove vsync disable/enable loop (fix #1383)

Also a small refactor due to repeated code.
The vsync flag in m_engine is now synchronized with the SDL state
during initial configuration of CApp.
---
 src/app/app.cpp | 73 ++++++++++++++++++++++---------------------------
 src/app/app.h   |  3 ++
 2 files changed, 35 insertions(+), 41 deletions(-)

diff --git a/src/app/app.cpp b/src/app/app.cpp
index ad5d02cb..47569c0a 100644
--- a/src/app/app.cpp
+++ b/src/app/app.cpp
@@ -115,7 +115,8 @@ CApplication::CApplication(CSystemUtils* systemUtils)
       m_configFile(MakeUnique<CConfigFile>()),
       m_input(MakeUnique<CInput>()),
       m_pathManager(MakeUnique<CPathManager>(systemUtils)),
-      m_modManager(MakeUnique<CModManager>(this, m_pathManager.get()))
+      m_modManager(MakeUnique<CModManager>(this, m_pathManager.get())),
+      m_engine(MakeUnique<Gfx::CEngine>(this, m_systemUtils))
 {
     m_exitCode      = 0;
     m_active        = false;
@@ -693,8 +694,6 @@ bool CApplication::Create()
     }
 
     // Create the 3D engine
-    m_engine = MakeUnique<Gfx::CEngine>(this, m_systemUtils);
-
     m_engine->SetDevice(m_device.get());
 
     if (! m_engine->Create() )
@@ -850,24 +849,9 @@ bool CApplication::CreateVideoSurface()
     int vsync = 0;
     if (GetConfigFile().GetIntProperty("Setup", "VSync", vsync))
     {
-        while (SDL_GL_SetSwapInterval(vsync) == -1)
-        {
-            switch(vsync)
-            {
-                case -1: //failed with adaptive sync?
-                    GetLogger()->Warn("Adaptive sync not supported.\n");
-                    vsync = 1;
-                    break;
-                case 1: //failed with VSync enabled?
-                    GetLogger()->Warn("Couldn't enable VSync.\n");
-                    vsync = 0;
-                    break;
-                case 0: //failed with VSync disabled?
-                    GetLogger()->Warn("Couldn't disable VSync.\n");
-                    vsync = 1;
-                    break;
-            }
-        }
+        m_engine->SetVSync(vsync);
+        TryToSetVSync();
+        vsync = m_engine->GetVSync();
         GetConfigFile().SetIntProperty("Setup", "VSync", vsync);
 
         GetLogger()->Info("Using Vsync: %s\n", (vsync == -1 ? "adaptive" : (vsync ? "true" : "false")));
@@ -876,6 +860,32 @@ bool CApplication::CreateVideoSurface()
     return true;
 }
 
+void CApplication::TryToSetVSync()
+{
+    int vsync = m_engine->GetVSync();
+    int result = SDL_GL_SetSwapInterval(vsync);
+    if (result == -1)
+    {
+        switch (vsync)
+        {
+        case -1:
+            GetLogger()->Warn("Adaptive sync not supported: %s\n", SDL_GetError());
+            m_engine->SetVSync(1);
+            TryToSetVSync();
+            break;
+        case 1:
+            GetLogger()->Warn("Couldn't enable VSync: %s\n", SDL_GetError());
+            m_engine->SetVSync(0);
+            TryToSetVSync();
+            break;
+        case 0:
+            GetLogger()->Warn("Couldn't disable VSync: %s\n", SDL_GetError());
+            m_engine->SetVSync(SDL_GL_GetSwapInterval());
+            break;
+        }
+    }
+}
+
 bool CApplication::ChangeVideoConfig(const Gfx::DeviceConfig &newConfig)
 {
     m_deviceConfig = newConfig;
@@ -884,26 +894,7 @@ bool CApplication::ChangeVideoConfig(const Gfx::DeviceConfig &newConfig)
     SDL_SetWindowSize(m_private->window, m_deviceConfig.size.x, m_deviceConfig.size.y);
     SDL_SetWindowFullscreen(m_private->window, m_deviceConfig.fullScreen ? SDL_WINDOW_FULLSCREEN : 0);
 
-    int vsync = m_engine->GetVSync();
-    while (SDL_GL_SetSwapInterval(vsync) == -1)
-    {
-        switch(vsync)
-        {
-            case -1: //failed with adaptive sync?
-                GetLogger()->Warn("Adaptive sync not supported.\n");
-                vsync = 1;
-                break;
-            case 1: //failed with VSync enabled?
-                GetLogger()->Warn("Couldn't enable VSync.\n");
-                vsync = 0;
-                break;
-            case 0: //failed with VSync disabled?
-                GetLogger()->Warn("Couldn't disable VSync.\n");
-                vsync = 1;
-                break;
-        }
-    }
-    m_engine->SetVSync(vsync);
+    TryToSetVSync();
 
     m_device->ConfigChanged(m_deviceConfig);
 
diff --git a/src/app/app.h b/src/app/app.h
index af385cf2..d238bde9 100644
--- a/src/app/app.h
+++ b/src/app/app.h
@@ -288,6 +288,9 @@ public:
 protected:
     //! Creates the window's SDL_Surface
     bool CreateVideoSurface();
+    //! Tries to set the SDL vsync state desired by the 3D engine
+    //! The final state of SDL vsync is set in the 3D engine afterwards
+    void TryToSetVSync();
 
     //! Processes the captured SDL event to Event struct
     Event       ProcessSystemEvent();